5D Mk3 video darker on computer than LCD???

So I've been doing some shooting at an event and exposed my shot to look a certain way on my 5D3. Then when I pull the shot onto my computer it looks a lot darker and more contrasty (as well as more saturated) than what was on my camera LCD. To the point that blue jackets that had detail in them look pure black on my computer. I've graded the video a bit to show you what my camera LCD looks like vs. the image on my computer, but this is tight turn around stuff that I am handing off to other editors so grading isn't really an option. Beyond that I would really like to trust that what is on my LCD when I shoot is actually what my shot is going to look like.

I've attached a couple of photos so you can see what I am talking about.

I am shooting using the 'Standard' picture profile, and viewing on a Macbook Pro which I've had no issues with in the past.

I don't have any direct experience with that exact combination of gear, but it's almost certainly something to do with video levels. Whereas the file in which the video is stored is capable of recording brightness levels between (assuming 8 bit) 0 and 255, which is sometimes called "full swing", many video devices only use the 16-235 range, which is sometimes called "studio swing". This was initially done so that certain voltage levels from the analogue world would be easy to maintain when converting to and from digital video, but these days, it's pretty much just an annoyance.

The 5D Mk. 2 was always famous for recording full-range, 0-255 video in such a way as to cause lots of postproduction software to assume it was recording limited-range, 16-235 video. The result of this is that the blacks get crushed and the highlights get blown out, to a degree that's sufficiently similar to what you're showing in your stills that I assume that's what's going on. Theoretically, this should all be automatically handled, using markers in the file, but it is rather poorly standardised and your problem is common.

If you want to prove it, sometimes you can establish more firmly that this is the problem by pulling it into something like Resolve or just After Effects and pushing the black level up, at which case it is sometimes possible to recover the lost detail, depending how the software is behaving in that particular circumstance. Sometimes the lost information gets cropped off and lost, sometimes not.

One decent solution is a piece of software called 5DtoRGB by Rarevision, which will do ProRes transcoding from 5D3 files (and those from other cameras) in such a way as to handle the video levels correctly. It was developed specifically to handle this sort of material and knows how to do so correctly. Disclosure: I know the developer, but I'm not financially involved. There are probably other things that can fix it. I'm not sure what.

If you just need to supply the material to someone else you can do so in confidence that there's nothing actually wrong with it. All 5D Mk. 2s and I assume 3s, and a lot of other cameras, do the same thing - and if the question comes up you can answer it for them.

Phil's right. The problem is most likely the software you're using to view the clips on your computer. I see this problem all the time when footage from Canon DSLRs is viewed in VLC. Since VLC assumes the video's usable range is 16-235, it ignores both full range shadow and highlight detail. The result is crushed blacks and clipped highlights.

QuickTime Player on the Mac is able to display Canon footage properly. Also, NLEs like Premiere display it properly as well.

If you want to ensure this will never, ever be a problem for anyone else working with this footage, the thing to do is transcode the footage using 5DtoRGB. It will remap the 8 bit full range video to 10 bit broadcast range and compress to ProRes. This will save all of the shadow and highlight detail. Anything that reads ProRes-compressed MOVs will then display it correctly.

Before going nuts hunting down a camera/lcd/computer/software problem, it might be easier than that. The Canon 5DMIII has an LCD brightness setting in the menu system. By default, it tends to be brighter than what is actually captured in the scene because it is tuned for daylight shooting. I shoot night sports and I tend to turn my LCD down 1 to 2 clicks from middle because the middle setting tends to be brighter than the what the camera is recording. If you are going to use the LCD to judge exposure, you really need to take a little time to tune it so that what the LCD displays is what the camera is recording. Same general rule with using an external LCD. Use it for for focus and composition, but shy away from using it to dial in exposure and color.